This protocol covers the management of localised rectal cancer situated in the upper third of the rectum in patients with mismatch repair proficient (MMR-p) / microsatellite stable (MSS) tumours. The anatomical location of this subtype significantly shapes the treatment strategy.
Localised rectal cancer in the upper third of the rectum; mismatch repair proficient / microsatellite stable (MMR-p/MSS). Because the benefit of radiotherapy is very limited for tumours at this anatomical site, the preferred management approach is analogous to that used for colon carcinoma.
Neoadjuvant chemotherapy is recommended based on tumour stage and nodal involvement. For certain high-risk presentations, a more intensive multimodal approach incorporating radiotherapy may be considered. The complete regimen, sequencing decisions, and full algorithm are available in the structured protocol.
The primary aim of neoadjuvant therapy is tumour downsizing, assessed by MRI at restaging after completion of treatment — restaging is an integral part of definitive management.
DOI: 10.1016/j.annonc.2025.05.528
For carcinomas in the upper third of the rectum, the benefit of RT is very limited; therefore, a procedure analogous to the approach for colon carcinoma may be preferred.
Algorithms for the management of localised rectal cancer in the upper third of the rectum are shown in Figures 1 and 2.
Neoadjuvant ChT is recommended for patients with cT2 N+ or cT3 Nany disease [I, A].
Neoadjuvant ChT is recommended for patients with cT4 Nany disease [V, A].
TNT should be offered to patients with cT4 or involved or threatened MRF [I, A].
Primary tumour response to RT and/or ChT can be substantial; therefore, restaging after initial therapy (neoadjuvant CRT, neoadjuvant ChT or TNT) is an integral part of definitive rectal cancer management.
For restaging with intended surgery: 3-4 weeks after completion of neoadjuvant ChT [I, A].
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